Integrated process condition sensing wafer and data analysis system

ABSTRACT

A process condition measuring device and a handling system may be highly integrated with a production environment where the dimensions of the process condition measuring device are close to those of a production substrate and the handling system is similar to a substrate carrier used for production substrates. Process conditions may be measured with little disturbance to the production environment. Data may be transferred from a process condition-measuring device to a user with little or no human intervention.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation-in-part of patent application Ser. No.10/718,269, filed Nov. 19, 2003, which claims the benefit of U.S.Provisional Patent Application No. 60/430,858 filed on Dec. 3, 2002,U.S. Provisional Patent Application No. 60/496,294 filed on Aug. 19,2003, and U.S. Provisional Patent Application No. 60/512,243 filed onOct. 17, 2003. The benefits of the filing dates of provisionalapplications Nos. 60/496,294 and 60/512,243 are also being directlyclaimed herein. Each of these applications is also incorporated hereinin its entirety for all purposes by this reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to semiconductor wafer processing, LCDdisplay glass substrate processing, magnetic memory disc processing, andother devices fabricated from thin film processes, and, morespecifically, to a system that can sense and record processingconditions and transmit data to a receiver.

2. Discussion of the Related Art

The fabrication of an integrated circuit, display or disc memorygenerally employs numerous processing steps. Each process step must becarefully monitored in order to provide an operational device.Throughout the imaging process, deposition and growth process, etchingand masking process, etc., it is critical, for example, thattemperature, gas flow, vacuum, pressure, chemical, gas or plasmacomposition and exposure distance be carefully controlled during eachstep. Careful attention to the various processing conditions involved ineach step is a requirement of optimal semiconductor or thin filmprocesses. Any deviation from optimal processing conditions may causethe ensuing integrated circuit or device to perform at a substandardlevel or, worse yet, fail completely.

Within a processing chamber, processing conditions vary. The variationsin processing conditions such as temperature, gas flow rate and/or gascomposition greatly affect the formation and, thus, the performance ofthe integrated circuit. Using a substrate to measure the processingconditions that is of the same or similar material as the integratedcircuit or other device provides the most accurate measure of theconditions because the material properties of the substrate is the sameas the actual circuits that will be processed. Gradients and variationsexist throughout the chamber for virtually all process conditions. Thesegradients, therefore, also exist across the surface of a substrate, aswell as below and above it. In order to precisely control processingconditions at the wafer, it is critical that measurements be taken uponthe wafer and the readings be available in real time to an automatedcontrol system or operator so that the optimization of the chamberprocessing conditions can be readily achieved. Processing conditionsinclude any parameter used to control semiconductor or other devicefabrication or any condition a manufacturer would desire to monitor.

Within the processing chamber a robot transports the test wafer orsubstrate. One example of a device incorporating a robot is manufacturedby the TEL Corporation. For more information about the robot andprocessing chamber, please refer to U.S. Pat. No. 5,564,889 to Araki,entitled “Semiconductor Treatment System and Method for Exchanging andTreating Substrate,” which is hereby incorporated by this reference inits entirety.

SUMMARY OF THE INVENTION

A process condition measuring device (PCMD) is disclosed that may bedelivered to a target environment, acquire a wide range of data andreturn to a handling system with little disruption to the targetenvironment or the tool containing the target environment. The PCMD isdesigned to have similar characteristics to the substrates normallyhandled by the tool. The characteristics of such substrates aregenerally specified by industry standards. Thus, for a system designedfor 300 mm silicon wafers, the PCMD has a silicon substrate and hassimilar physical dimensions to those of a 300 mm wafer. Components maybe located within cavities in the substrate to keep the profile of thePCMD the same as, or close to that of a 300 mm wafer. Because of itsdimensions and its wireless design, the PCMD may be handled by a robotas if it were a 300 mm wafer. It may undergo the process steps undergoneby wafers such as etch, clean, photolithography etc. The PCMD recordsprocess conditions such as temperature, pressure and gas flow rateduring processing and uploads the data when requested. Conditions duringtransport and storage may also be monitored and recorded.

Making a PCMD employs multiple process steps similar to those used insemiconductor IC manufacturing. An insulating layer is deposited overthe substrate. A conductive layer is deposited and patterned to formtraces. Cavities are formed in the substrate surface and components areplaced in those cavities. Components are then bonded to traces to formelectrical connections. A passivation layer may then be deposited overthe surface to protect the substrate, components and the wire bonds.

PCMDs may be made compatible with harsh environments by protectingcomponents from chemical or electrical damage. Critical components mayhave covers similar to parts used in packaging ICs. Covers may also bemade of specialized materials such as sapphire or, for electricalprotection, silicon or metal. PCMDs may also be adapted to hightemperatures by incorporating a temperature compensating circuit toallow an oscillator to perform outside its specified temperature range.

A handling system provides a docking station or base for a PCMD. ThePCMD exchanges data with an electronics module when it is docked in thehandling system and also receives power from the electronics module. Thehandling system may comprise an electronics module within a standardsubstrate carrier such as a front opening unified pod (FOUP). Thisallows the handling system to be highly integrated with a tool or withfacility automation. The PCMD may be moved to and from the FOUP by thetool and the FOUP may be moved from one tool to another by the facilityautomation. The FOUP provides a clean environment for the PCMD where itmay be stored or transported. In addition, loading stations for FOUPsare normally provided with RFID readers to determine the identity of theFOUP and relay the information to a tracking system via a network. Byconnecting the electronics module in the FOUP to an RFID transceiver,data from the electronics module may be sent to the network where it maybe accessed.

Data acquired from the sensors may be compressed by the electronicsystem on the PCMD prior to non-volatile storage and/or transmission ofthe data. The data are represented by temporal and/or spatialdifferences, thereby significantly reducing the amount of data necessaryto represent the sensor measurements. Storage of certain of the acquireddata may also be omitted if the condition being monitored by the sensorsmeets certain criteria. A reduction in the amount of data reduces thesize required for a non-volatile memory on the PCMD, conserves itsbattery power and extends the period of time (runtime) that the PCMD mayoperate to acquire data between battery charges.

A handling system may have an alignment module that may move a PCMDwithin a handling system in order to facilitate communication betweenthe PCMD and the electronics module of the handling system, as well ascharging the PCMD battery. Vertical and rotational motion of a PCMD maybe achieved by a rotation stage or wheels supporting its perimeter.Raising a PCMD may allow better coupling to the electronics module.Lateral movement of the PCMD may be achieved by a moving belt or wheelthat is brought into contact with the lower surface of the PCMD to movethe PCMD into position. As an alternative to raising the wafer, aflexible sheet containing a battery charging and/or communication coilmay be attached to the underside of the electronics module in a mannerso that it may be lowered onto the exposed surface of the PCMD.

A PCMD may have a pattern on its surface that allows its orientation tobe determined. Greycode printed on the edge of a surface of a PCMD mayallow the rotational orientation of the PCMD to be determined. Greycodereaders may be installed in a handling system so that the orientation ofthe PCMD is known before it is sent on a survey and after it returns.Such a system does not require movement of the PCMD relative to thereaders in order to determine orientation.

A PCMD may have temperature compensation circuitry to allow componentsto operate at high temperatures. An oscillator within a clock circuitmay have its bias adjusted as the temperature changes so that theoscillator continues to function beyond its specified temperature range.

Each of the PCMD and the electronics module within the handling systemmay include a microcontroller based computing system that controls theacquisition, processing, storage, and transmission of data from thesensors on the PCMD, control of the limited amounts of battery poweravailable for use by each, the replenishment of that battery power, andother similar types of processing and control functions.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a plan view of Process Condition Measuring Device (“PCMD”)100.

FIG. 1B is a depiction of components within PCMD 100.

FIG. 1C is a cross section of a single component within PCMD 100.

FIG. 1D is a plan view of an embodiment of PCMD 100 with graycodecoding.

FIG. 1E shows PCMD 100 spinning about a central axis 199.

FIG. 2A is a perspective view of the back of Handling System (“HS”) 200.

FIG. 2B is a perspective view of the front of HS 200.

FIG. 2C is a processing tool 260 having a robot that transferssubstrates between a substrate carrier and a processing chamber.

FIG. 2D is a cross-sectional view of processing tool 260.

FIG. 3A is a cross section of an embodiment of PCMD 100.

FIG. 3B is a cross section of another embodiment of PCMD 100.

FIG. 4A is a flowchart depicting the steps of making the cross sectionshown in FIG. 3A.

FIG. 4B is a flowchart depicting the steps of making the cross sectionshown in FIG. 4A.

FIG. 5A is a cross-section of an E-coil 510 inductively charging a coil508.

FIG. 5B is a cross-section of an E-coil 510 inductively charging a coil508 with a magnetic conductive layer 555.

FIG. 6 is a circuit diagram of a high temperature crystal oscillatorcircuit 660.

FIG. 7 shows a PCMD 700 having four transmitters 728–731.

FIG. 8A shows a handling system 880

FIG. 8B shows a portion of a PCMD having greycode 850.

FIG. 8C shows an alignment module 881.

FIG. 8D shows handling system 880 with PCMD 800 in the normal position.

FIG. 8E shows handling system 880 with PCMD 800 in the raised position.

FIG. 8F shows alignment module 881 with PCMD 800.

FIG. 8G shows alignment module 881 moving PCMD 800 laterally.

FIG. 8H shows alignment module 881 raising and rotating PCMD 800.

FIG. 8I shows E-coil 810 moving vertically towards PCMD 800.

FIG. 9A shows various communication systems between PCMD 900, handlingsystem 980 and software application 987 that are operated in a manualmode.

FIG. 9B shows various communication systems between PCMD 900, handlingsystem 980 and a controlling computer 983 that operate in an automaticmode.

FIGS. 10A–10D show different examples of lids protecting components ofPCMDs.

FIG. 11A is a plan view of another embodiment of a PCMD and FIG. 11B across-section thereof taken at section B—B of FIG. 11A.

FIG. 12 is a block diagram of a microcontroller included in the PCMD andits use.

FIG. 13 is a flowchart showing acquisition of data and its compressionby the microcontroller.

FIG. 14 is an example table of data obtained by the process illustratedin FIG. 12.

FIG. 15 shows an example application of the PCMD when measuringtemperature.

FIG. 16A shows a wafer handling system that is a modified version ofthat shown in FIGS. 8A and 8D through 8I.

FIG. 16B shows a portion of the wafer handling system of FIG. 16A froman internal view that is orthogonal thereto.

FIG. 16C is an enlarged view of a portion of FIG. 16B, illustrating thecharging of the PCMD batteries.

FIG. 16D is a top view of the PCMD within the handling system of FIG.16A.

FIG. 17 is a schematic block diagram of an electronic system within thewafer handling system shown in FIGS. 16A–16D.

FIG. 18 is a schematic block diagram of an electronic system on a PCMD.

DESCRIPTION OF EMBODIMENTS

The measurement system in one embodiment measures processing conditionsin various locations of a wafer or substrate and records them in memoryfor later transmission or downloading of the process conditions. Inanother embodiment of the measurement system where a processing chamberhas windows capable of data transmission, the system is additionallycapable of transmitting the processing conditions in real time to a dataprocessing device.

FIG. 1A illustrates process condition measuring device (“PCMD”) 100, anembodiment of the present invention. PCMD 100 is part of a processmeasurement system, the other components of which will be describedlater with reference to FIG. 2. PCMD 100 comprises a substrate such as asilicon wafer, glass substrate, or other substrates well known in theart. Substrate 102 (not visible in plan view) is preferably a siliconwafer and may be of any diameter but is preferably an 8 or 12 inchdiameter wafer. The diameter is preferably that of wafers or othersubstrates being processed in the processing chamber for which the PCMDis to be used. If integrated circuits are being fabricated on siliconwafers in the processing chamber, the substrate of the PCMD ispreferably also silicon but need not necessarily be doped.

A number of components are integrated to form PCMD 100. Sensors 124 aredistributed about PCMD 100 and are, therefore, capable of detectinggradients in various processing conditions across the surface of thesubstrate. Sensors 124 are connected to the microprocessor 104 throughconductive traces 120. Conductive traces 120 preferably comprisealuminum, but may comprise any conductive material. The formation ofPCMD 100, including the conductive traces and the other components willbe described later with reference to FIGS. 3 and 4. Microprocessor 104preferably includes flash memory cells for storing the processingconditions and other instructions necessary for the operation of PCMD100. However, the flash, or other type memory, may alternatively be partof a discrete EPROM or EEPROM rather than being an integral part ofmicroprocessor 104. Clock crystal 132 generates a timing signal used invarious operations of PCMD 100. Transmitter 128 preferably comprises alight emitting diode (LED) for transmitting data. Around transmitter 128is a radio frequency (RF) inductive coil 108 that receives data andserves to inductively charge power sources 112A and 112B. In oneembodiment of the invention, transmitter 128 may also act as atransceiver and receive data as well as transmit data. Additionally,coil 108 may also act not only as a receiver, but also as a transmitter.Thus, coil 108 may serve as a receiving unit that may receive both dataand power.

In the embodiment illustrated, power sources 112A and 112B are thin filmlithium ion batteries that are equidistant from the center of the PCMD100. The thin 0.25 mm thick power sources allow for a thin overall PCMDstructure with a thickness of 0.70 mm, which is comparable to aproduction wafer and compatible with the robot arms typically used inwafer handling procedures. These power sources have previously beencommon to under-skin medical implants where they are similarlyinductively charged. Power sources 112A and 112B are capable ofcontinuous operation at temperatures up to roughly the melting point oflithium, around 180 degrees Centigrade. The equidistant spacing of thepower sources 112A, 112B shown in FIGS. 1D and 1E, maintains the balanceof PCMD 100 which is beneficial in situations where PCMD 100 may bespinning within a processing module. FIG. 1E shows the central axis 199of PCMD 100 passing through the center of PCMD 100. Central axis 199 isperpendicular to a surface 198 of PCMD 100. The center of gravity ofPCMD 100 lies along central axis 199. Central axis 199 is the axis ofrotation when PCMD is spun in a processing module. Batteries 112A and112B are equidistant from central axis 199 and are 180 degrees apart.Thus, where batteries 112A and 112B are of the same mass, their combinedcenter of gravity is along central axis 199. Additionally, the othercomponents are arranged in order to maintain as uniform a mass andthermal profile as possible. A passivation layer 116 and an optionalshield layer are formed above all of the components of PCMD 100 in orderto protect the components and substrate from various processingconditions. The layers that make up PCMD 100 will be described infurther detail later with reference to FIGS. 3 and 4.

Coil 108 of FIG. 1 may be located within a cavity in the substrate. Coil108 may be extremely thin so that it does not add to the overall heightof the PCMD 100 when placed on the surface or in shallow cavity. Forexample, FIG. 5A shows a cross-section of a coil 508 in a cavity and itsinductive coupling with an external coil 510 for inductive charging ofthe batteries on the substrate and/or transmitting data between the two.In this example, coil 508 includes several windings of increasingradius. However, coil 508 is only one winding in height so that thethickness of coil 508 is approximately the same as the thickness of theconductor used for the winding. Coil 508 may be located in the middle ofthe wafer as shown in FIG. 1A. FIG. 5A shows a similar coil 508 in acavity 550 within the substrate 502. FIG. 5A shows the position of coil508 with respect to an E-coil 510 located in electronics module 508.E-coil 510 may be used to supply power to the PCMD 100 by inducing anelectrical current in the windings of coil 508. E-coil 510 may also beused to transmit data to coil 508. Thus, the induced field is used totransmit both power and data to PCMD 100. E-coil 510 typically providesan RF field at a frequency of 13.56 MHz. One advantage of placing coil508 so that its axis passes through the center of the PCMD is that itmay easily be aligned with an external unit such as E-coil 510 becausethe rotational orientation of PCMD 100 does not affect the position ofthe coil 508. Thus, E-coil 510 may serve as a transmitting unit that maytransmit both power and data.

FIG. 5B shows coil 508 having a magnetic conductive layer 555. Magneticconductive layer 555 may be made of a ferrite material. The inducedfield is concentrated in magnetic conductive layer 555 and so themagnetic field in the substrate 502 is minimized. Where the substrate502 is made of a conductive material such as doped silicon this isespecially advantageous. When the RF field extends into a conductivesubstrate the changing magnetic field in the substrate induces eddycurrents. These eddy currents dissipate the RF field and result in alower efficiency of power transfer between E-coil 510 and coil 508. Inaddition, eddy currents flowing through a conductive substrate may heatthe substrate and could damage PCMD 100.

Clock crystal 132 (FIG. 1B) is part of a crystal oscillator circuit.FIG. 6 shows an example of a high temperature crystal oscillator circuit660 that may be used for this application. High temperature crystaloscillator circuit 660 is comprised of a conventional crystal oscillatorcircuit 661 and a biasing circuit 670. The conventional oscillatorcircuit 661 includes a crystal 632, amplifier 662 and capacitors 663 and664. The amplifier 662 and capacitors 663 and 664 are within CPU 604,while the crystal 632 is external to the CPU. The biasing circuit 670includes counter 671, ring oscillator 672 and bias control unit 673within CPU 604. In addition, biasing circuit 670 includes a series ofresistors 675 that are connectable to the crystal under the control ofbias control unit 673. Resistors 675 are external to CPU 604.

Amplifier 662 provides positive feedback to maintain the oscillatorsignal. Amplifiers available in commercially produced ICs, such asamplifier 662, are specified as working over a certain range oftemperature, for example 0–85 degrees centigrade. When the temperatureis higher than the specified range, conventional oscillator circuit 661may no longer function correctly. Threshold voltages of components inthe amplifier may shift which eventually causes oscillation to cease orstartup to fail. When amplifier 662 is working within its specifiedtemperature range it produces a signal with a 50% duty cycle. Withincreasing temperature the duty cycle increases and as the duty cycleapproaches 100% conventional oscillator circuit 661 ceases to function.

Biasing circuit 670 overcomes this problem by biasing the input ofamplifier 662 in order to maintain a 50% duty cycle. Counter 671 usesthe input from ring oscillator 672 to determine the duty cycle. Counter671 counts the number of clock cycles of ring oscillator 672 during the“on” phase of the output of amplifier 662. It then counts the number ofclock cycles of ring oscillator 672 during the “off” phase of the outputof amplifier 662. The counts are sent to the bias control unit 673 wherethe duty cycle is determined. If these counts are equal then the dutycycle is 50%. If the count for the “on” phase exceeds the count for the“off” phase, then the duty cycle is greater than 50%. The frequency ofring oscillator 672 is greater than the frequency of the output ofconventional oscillator circuit 661. Typically, the conventionaloscillator circuit has an output frequency of about 32 kHz while thering oscillator has an output frequency of about 400 kHz–4 MHz. Ringoscillator 672 may suffer from a change in frequency at hightemperature. However, because the output for two periods are compared,the absolute value of the output over a given period does not affect thedetermination of duty cycle.

If the duty cycle is determined to be greater than 50% the bias controlunit 673 may modify the bias input 676 to reduce the duty cycle. Thismay be done in a number of ways. In the example shown in FIG. 6, aseries of resistors 675 of different resistances are connected between abias voltage and bias input 676. The bias voltage used may be Vcc on theCPU chip. In this way, the voltage and current at the input of amplifier662 may be controlled to bring the duty cycle back to 50%. Using thistechnique, the effective range of high temperature crystal oscillatorcircuit 660 may be extended from the stated upper limit of the CPU chip604 (85 degrees centigrade) to as high as 150 degrees centigrade. Thisallows PCMD 100 to use standard parts in conditions that would otherwiserequire custom parts. As alternatives to using resistors 675, othercomparable means may be used to modify impedance such that a change inbias is achieved. These alternatives include an electronicpotentiometer, transistor, voltage resistor network.

Transmitter 128 shown in FIG. 1A may be used to transmit data from thePCMD. Here, transmitter 128 is an LED. This is a more energy efficientway to transmit data than using RF via coil 108. For transmission fromthe PCMD energy efficiency is important, whereas for transmitting datato the PCMD energy is generally not as critical so that RF may be used.In the example shown in FIG. 1A the transmitter is located at the centerof the upper surface of the PCMD. Placing LED 128 in the center allowsit to be more easily aligned with any external receiver because theposition of LED 128 with respect to the external receiver will not varyif PCMD 100 is rotated. This may be important where PCMD 100 is rotatedduring a survey as occurs in some environments.

In another embodiment shown in FIG. 7, four transmitters 728–731 arelocated around coil 708. This example also uses LEDs as transmitters728–731. Using multiple LEDs allows a receiving unit 777 in anelectronics module 778 to receive a good signal even where receivingunit 777 is not aligned with the center of PCMD 700. Where one LED atthe center of a PCMD is used (as in FIG. 1) but the receiving unit inthe electronics module is offset from the center, a poor signal or nosignal may be received because the LED directs light in a limited cone.The receiving unit 777 may be offset because the E-coil occupies a spacecovering the center of the PCMD. Thus, it is desirable to have one ofLEDs 728–731 aligned with the offset position of the receiving unit 777.This requires more than one LED (four, in this example) so that one LEDis below the receiving unit regardless of the rotational orientation ofthe PCMD 700. However, for energy efficiency it is desirable to transmitvia only one LED. Therefore, a technique is provided for determining theoptimum LED to transmit data.

The optimum LED is determined as part of a hand-shaking routine betweenthe electronics module 778 and the PCMD 700. First, the electronicsmodule 778 sends a signal to the PCMD 700 via the RF coil 708, tellingPCMD 700 to begin transmission. The PCMD 700 begins transmitting usingLED 728. If the electronics module 778 does not receive a signal after apredetermined time, another signal is sent to the PCMD 700 requesting atransmission. The PCMD 700 transmits using LED 729. If receiving unit777 receives no signal, then LED 730 is used. If no signal is receivedfrom LED 730, then LED 731 is used. Because LED 731 is directly belowreceiving unit 777, the signal is received and LED 731 is identified asthe optimum LED The PCMD then uses only the optimum LED 731 and may turnoff the other LEDs 728–730 to conserve energy. This process of selectingone of the LEDs to engage in the communication is carried out on thePCMD 700 by the processing unit 104. A processor within the electronicsmodule 778 controls its operation, which is more limited. More LEDs maybe used depending on the configuration of the receiving unit or units.LEDs may be arrayed in different locations and pointed in differentdirections depending on where the data is to be sent.

Utilizing the limited storage capacity of the power sources efficientlyis desirable to maximize the amount of data and measurement time of thePCMD. The sensor groups that are activated are user selectable, thegroups are only activated when necessary. Outputs from selected groupsare multiplexed and only written into memory at selected intervals. Theoutput is also compressed to minimize the amount of time and energyneeded to store the data.

As defined herein, “processing conditions” refer to various processingparameters used in manufacturing an integrated circuit. Processingconditions include any parameter used to control semiconductormanufacture or any condition a manufacturer would desire to monitor suchas, but not limited to, temperature, etch rate, thickness of a layer ona substrate, processing chamber pressure, gas flow rate within thechamber, gaseous chemical composition within the chamber, positionwithin a chamber, ion current density, ion current energy, light energydensity, and vibration and acceleration of a wafer or other substratewithin a chamber or during movement to or from a chamber. Differentprocesses will inevitably be developed over the years, and theprocessing conditions will, therefore, vary over time. Therefore,whatever the conditions may be, it is foreseen that the embodimentsdescribed will be able to measure such conditions. In addition tomeasuring these conditions during the processing of semiconductorwafers, the systems and techniques described herein may also be appliedto the monitoring similar conditions during processing of other types ofsubstrates.

Sensors 124 are used for detecting various processing conditions aremounted on or fabricated in substrate 102 according to a well-knownsemiconductor transducer design. For measuring temperature, a populartransducer is an RTD or thermistor, which includes a thin-film resistormaterial having a temperature coefficient. A magneto-resistive materialmay also be used to measure the temperature through the amount ofmagnetic flux exerted upon substrate 102. A resistance-to-voltageconverter is often formed within the substrate between distal ends ofthe resistive-sensitive material (either thermistor or magneto-resistivematerial) so that the voltage may easily be correlated with atemperature scale. Another exemplary temperature sensor includes athermocouple made of two dissimilar conductors lithographically formedin the layers of the substrate. When the junction between the conductorsis heated, a small thermoelectric voltage is produced which increasesapproximately linearly with junction temperature. Another example of atemperature sensor includes a diode that produces a voltage thatincreases with temperature. By connecting the diode between a positivesupply and a load resistor, current-to-voltage conversion can beobtained from the load resistor. Another sensor is a piezoelectricdevice such as a quartz tuning fork fabricated from quartz crystal cuton a crystal orientation which exhibits a temperature dependentfrequency of oscillation. The sensor's oscillating frequency can bereferenced against a master oscillator formed by a piezoelectric devicesuch as a quartz tuning fork, which is fabricated from a crystaloriented to minimize frequency change with temperature. The frequencydifference between the sensor and master oscillator would provide adirect digital temperature dependent signal. Piezoelectric sensors mayalso be used to sense mass change to measure deposition mass and ratesor other process conditions.

Sensors 124 may also be used to measure pressure, force or strain atselect regions across substrate 102, either as a discrete sensor or asensor integrally formed in the layers of substrate 102. There are manytypes of pressure transducers capable of measuring the atmosphericpressure exerted upon the wafer. A suitable pressure transducer includesa diaphragm-type transducer, wherein a diaphragm or elastic elementsenses pressure and produces a corresponding strain or deflection whichcan then be read by a bridge circuit connected to the diaphragm orcavity behind the diaphragm. Another suitable pressure transducer mayinclude a piezoresistive material placed within the semiconductorsubstrate of substrate 102. The piezoresistive material is formed bydiffusing doping compounds into the substrate. The resultingpiezoresistive material produces output current proportional to theamount of pressure or strain exerted thereupon.

Sensors 124 may also be used to measure flow rate across substrate 102.In addition, humidity and moisture sensors can also be formed uponsubstrate 102. A well-known method for measuring flow rate, a hot-wireanemometer, may be incorporated into substrate 102. Fluid velocity isbased upon the frequency of vortex production as a streamlined fluidicflow strikes a non-streamlined obstacle positioned on or in substrate102. Measurement of fluid flow generally involves the formation ofspecial vortices on either side of the obstacle. Thus, an alternatingpressure difference occurs between the two sides. Above a threshold(below which no vortex production occurs), the frequency is proportionalto fluid velocity. Of many methods of detecting the alternating pressuredifference, a hot thermistor is preferably placed in a small channelbetween the two sides of the obstacle. The alternating directions offlow through the capitalized channel periodically cool the self-heatedthermistor thereby producing an AC signal and corresponding electricpulses at twice the vortex frequency. Therefore, an obstacle protrudingfrom substrate 102 in front of a thermistor can provide solid-state flowrate measurement. Heat can be transferred between self-heatedthermistors placed in close proximity to each other. Fluid flowtransfers thermal energy between the adjacent thermistors causing athermal imbalance proportional to mass flow. Two or more adjacentsensors can be arrayed to measure flow along a vector, or multiple flowvectors may also be sensed. The thermal imbalance can be detected toproduce a DC signal related to mass flow. Flows in multiple directionscan be compared to detect flow vectors.

Sensors 124 can also be used to measure the gaseous chemicalconcentration placed upon substrate 102. Chemical composition sensorsutilize a membrane which is permeable to specific ions to be measured.Ideally, the membrane should be completely impermeable to all otherions. The conductivity of the membrane is directly proportional to thetransport of select ions which have permeated the membrane. Given thevariability of membrane conductivity, measurements can be taken whichdirectly correlate to the amount of chemical ions present within theambient surrounding substrate 102.

Sensors 124 may also be used to measure ion current density and ioncurrent energy with a parallel plate structure, an array of collectingplates, and collecting plates with control grids supported above thecollecting plates. The current flowing between parallel plates, or tothe array of collecting plates will increase with ion current density.Ion current energy can be detected by applying a constant or varying DCpotential on the grids above the plates. This will modulate current flowwith ion current energy allowing the energy distribution to be detected.This is useful in monitoring and regulating a deposition or etchingprocess.

A piezoelectric transducer/sensor may also be integrated into substrate102 to measure the resonant frequency of a layer and thus the mass orthickness of the layer.

Additionally, sensors 124 can also be used to detect a change inposition or displacement of an object spaced from substrate 102.Exemplary displacement transducers include electro-optical devices whichcan measure photon energy (or intensity) and convert photon energy to anelectric field or voltage. Relatively well known electro-optical devicesinclude light-emitting diodes, photodiodes, phototransistors, etc.,which can be formed upon a semiconductor substrate or discrete devicesembedded within the substrate or placed on the surface. Displacementsensors are used to provide accurate information about electrode spacingwithin an etch or deposition chamber, and can also provide spacinginformation between a wafer and corresponding masks and/or radiationsource.

FIG. 1B illustrates some components of PCMD 100 within substrate 102.FIG. 1B is not a true cross section of PCMD 100, but only serves toillustrates how the components such as sensors 124, oscillator 132,microprocessor 104, power source 112, resistor 113, and capacitor 115are located within recesses formed in PCMD 100. Further details of thisare shown in FIG. 1C, where a component 140 is affixed to a cavity 142within substrate 102 (and the other layers on substrate 102) withbonding material 144. Bond wires 148 electrically couple the component140 with conductive traces 120 seen in FIG. 1A. Bond wires 148 andcomponent 140 are covered with potting material 152.

In the case where the PCMD 100 measures a parameter through a number ofsensors distributed across the wafer substrate 102 that are temperaturesensitive, it is desirable that the sensors, processing unit 104 andother components be mounted on the substrate in a manner that does notsignificantly change or perturb the temperature across the wafer. Thisis particularly important when the measured parameter is temperature. Atemperature PCMD 100 is generally used to measure the temperatures thatexist across a wafer or other substrate during an actual processingoperation, such as when being heated by a hot plate or when positionedwithin a processing chamber. The PCMD 100 is thus desirably made to havethermal properties as close to those of the actual wafer being processedas is reasonably possible. This improves the accuracy of the temperatureprofile readings across the test wafer 102 and eliminates or minimizesthe amount of processing that needs to be done to compensate or correctthe temperature readings for perturbing effects of the circuit elementsadded to the wafer.

The individual components are therefore preferably carried by the wafer102 (FIGS. 1B and 1C) in a manner that does not alter the thermalcharacteristics across the wafer. The components, where possible andparticularly in the case of the temperature sensors 124 and otherelements, are bare integrated circuit die (chips) without the usualcommercial package surrounding them. Thermal compatibility is thusmaintained with a silicon wafer 102 since the dies are primarily alsosilicon material. An individual die is then connected by wire bondsdirectly from bonding pads on the die to the conductive traces adjacentthe die. The conductive traces extend across the surface of the waferwith a layer of dielectric therebetween.

Although the circuit chips and other components could be mounted on thetop surface of the test wafer, it is preferable to have them containedin cavities 142 formed in the surface of the wafer. Since the die areprimarily of the same material as the silicon wafer substrate, anyremaining space in the cavities around the die is filled with material152 that has substantially the same thermal characteristics as thesilicon substrate and die. This restores, in the area of each cavity,the thermal characteristics of the wafer 102 to that of the area beforethe cavity was formed. Perturbations of the temperatures being measuredacross the wafer 102 that might be caused by those of the addedcomponents that can be mounted in this manner are thus eliminated or atleast reduced to a level that provides accurate results without havingto process the data obtained from the sensors to compensate for suchperturbations.

The depth of the each cavity 142 is preferably about that of the dieplaced within it, plus the thickness of the bonding material 144. Thebonding material 144 that attaches the die 140 within the cavitypreferably thermally integrates the die 140 to and with the wafer 102.That is, the characteristics of thermal conductivity (or the inverse,thermal resistance RTH) and thermal capacitance (CTH) of the layer 144are made to be as close to that of the wafer 102 as possible. Formechanical stability, an equivalence of their coefficient of thermalexpansion (TC) is also desired. Although the layer 144 could also bemade electrically conductive, thereby placing the substrate of theintegrated circuit die 140 at the same potential as the wafer 102, it ispreferably to electrically insulate the die from the substrate 102. Thepotential of the individual die can then be controlled by connecting itto one of the conductive traces across the surface of the wafer 102.

The bonding material layer 144 is preferably an epoxy material filledwith small particles of diamond (such as in a range of 2–9 microns indiameter) because of diamond's extremely high thermal conductivity.Diamond is sufficiently electrically non-conductive to be positionedbetween two semiconductors. The viscosity of the starting epoxy materialand the concentration of the diamond particles are preferably chosen sothat the viscosity of the combination remains low enough to flow into avery thin layer 144 of uniform thickness. The layer 144 thereforeintroduces little or no thermal resistance or capacitance between thedie 140 and the wafer substrate 102.

The potting material 152 is also preferably made to have thermalcharacteristics as close to that of the wafer as possible. An example isto use a polymer such as a polyimide that is filled with small particleshaving thermal characteristics that match those of the wafer 102, onesuitable material being aluminum nitride. If the die 140 is beingelectrically isolated from the wafer 102, these particles are coatedwith an electrical insulation material, silicon dioxide being anexample. Since the polymer material will usually have thermalcharacteristics that do not match those of the wafer 102, it is filledover fifty percent by volume with such particles, and preferably overseventy or eighty percent. This composite material is placed around andover the circuit die in a liquid form and allowed to cure into a solid,as shown in FIG. 1C.

It is of course very beneficial to thermally integrate the temperaturesensors with the wafer substrate of a temperature measuring device inorder to obtain readings of the temperature of the wafer. The sensor maybe of a type formed on an integrated circuit chip and therefore mountedto the wafer substrate in the manner described above. In response tobeing provided power, such a circuit chip outputs an electricalparameter that is proportional to its temperature. An example is anintegrated circuit temperature sensor available from NationalSemiconductor Corporation, identified as LM20, which may be obtained asa bare chip without the normal packaging. This chip outputs an analogvoltage of a level dependent upon its temperature, and which thereforecan be electronically converted to a temperature measurement.

The mounting of other integrated circuit chips and components to thewafer 102 in the manner described above has the beneficial effect ofreducing their effect on the measurement of such temperature sensors.This is particularly beneficial when the wafer instrument is measuringtemperatures that are rapidly increasing or decreasing. In this case, anattached chip or other component not thermally integrated with the wafersubstrate could cause a transient cold or hot spot, respectively, tooccur on the wafer that affects the instantaneous measurement of one ormore of the sensors.

FIG. 1D illustrates an embodiment of PCMD 100 with graycode coding 150around the edge. This graycode coding is used to determine the positionor rotation of the PCMD with regard to reference axes, and will bedescribed in more detail later.

FIGS. 2A and 2B illustrate PCMD handling system (“HS”) 200. Handlingsystem 200 generally speaking includes a user interface and variouselectronic components, including a microprocessor and memory, fortransferring data to and from a number of PCMDs and for configuring,recharging, and transporting the PCMDs.

Cassette 204 can accommodate several PCMDs and may be located at anopening of a processing chamber or a tool that has multiple processchambers such that a robot arm may automatically place or remove thePCMDs within one of the various slots 250 of cassette 204. Cassette 204is a standard cassette that is compatible with a range of tools.Alternatively, a modified cassette could be used as long as it iscompatible with the mechanical automation used within the facility wherea PCMD is used. FIG. 2A illustrates the back or process side of HS 200.The PCMDs are inserted and removed from the process side. One PCMD 100is shown just below electronics module 208 and above charging board 216.When a PCMD is placed in the cassette, its power source(s) areinductively charged by electronics module 208 and charging board 216.The source of the power is batteries positioned behind battery holdercaps 212. An additional charging board may also be present in apush/pull configuration to increase the inductive charging rate.Although the embodiments described thus far utilize inductive charging,other embodiments may utilize optical components for charging and datatransmission, although with the use of these optical componentsalignment is much more critical to proper recharging and datatransmission. And a wire connection may alternatively be made when thePCMD 100 is placed into the cassette 204 for battery charging and/ordata transmission but this is less convenient and thus not preferred.

In any embodiment, the PCMDs may include graycode coding around theperiphery, and HS 200 may also have optical sensors that detect thealignment of the PCMD while in the cassette 204 with the graycode coding(FIG. 1D). Therefore, the wafer can be optimally aligned for datarecharging and data transmission. Additionally, if a PCMD returns with adifferent alignment than it departed with, this may indicate that itrotated some amount in the processing chamber, and that this rotationshould be taken into account when analyzing the processing conditiondata gathered from the chamber or other environment.

Substrates are typically stored and transported in a substrate carriersuch as cassette 204. Processing tools are adapted to a particularstandard substrate carrier. Typical tools have robots that movesubstrates from a substrate carrier through the tool and back to asubstrate carrier. Substrate carriers within a facility areinterchangeable so that the robot may be calibrated to a substratecarrier and continue to operate with similar substrate carriers withoutbeing recalibrated. A single substrate carrier standard is used so thata substrate carrier may be moved from one tool to another and the robotin each tool may transport substrates to and from the substrate carrier.

FIG. 2C shows a view of a processing tool 260 that includes a robot 261that transfers substrates to a processing chamber 269. The robot has amechanical arm 262 with a blade (or endeffector) 263 attached to the endof arm 262 that can pick up a substrate 264. Substrate 264 is held in asubstrate carrier 265 so that the blade 263 may be extended undersubstrate 264 to pick up substrate 264. Blade 263 may rise to liftsubstrate 264 or substrate 264 may be lowered onto blade 263. Theposition of substrate 264 is important to allow blade 263 to pick upsubstrate 264. Typically a substrate carrier has multiple slots, eachslot holding one substrate. A slot is open on one side to allow asubstrate to be removed. A slot establishes the position of a substrate.In particular the height of a substrate above the bottom surface of thecassette is established to allow a substrate to be picked up. The bottomsurface of the cassette may be placed on a platform and the position ofa substrate above the platform is accurately established so that therobot may automatically pick it up.

FIG. 2D shows a side view of processing tool 260 showing blade 263extending under substrate 264 while substrate 264 is in substratecarrier 265. The height of substrate 263 above the bottom surface 266 ofsubstrate carrier 265 is established. Each slot establishes the positionof a substrate so that blade 263 may be inserted between substrateswithout touching them. A processing tool robot is generally calibratedto a standard substrate carrier so that substrates may be picked up ordropped off to any slot. Standard substrate carriers are used throughouta particular facility so that various tools are calibrated to a standardsubstrate carrier. Thus, substrates are repeatedly presented to a robotat the same positions and no recalibration is needed from one substratecarrier to another. Presenting a PCMD to a robot at one of thecalibrated positions allows the PCMD to be transferred as if it were astandard substrate. Incorporating an electronics module in a single unitwith a substrate carrier that presents a PCMD in this way provides aconvenient location to exchange data and to recharge the PCMD in anautomated fashion.

In some embodiments a HS is adapted for use with a substrate carrierother than cassette 204 such as a front opening unified port (FOUP) thusforming a handling system (or dock) where a PCMD may be stored,transported, charged and in which data may be exchanged. FIG. 8A showsan example of such a handling system 880. A FOUP is an industry standardcarrier for handling 300 mm wafers. The specifications of both the FOUPand of 300 mm wafers are set by industry standards established by SEMI.A FOUP is particularly suitable for use as part of a HS. It is designedto hold wafers and to be compatible with a wide range of semiconductorprocessing and metrology equipment. It protects the PCMD and provides aclean environment for it so that the PCMD does not pick up contaminationthat might be brought into a target environment. When handling system880 is placed at a loading station for a particular piece of equipment,the PCMD may be robotically transferred from the handling system to atarget environment such as a process chamber using the same robot thatis used for 300 mm wafers without requiring reconfiguration. Thus,handling of a PCMD may be identical with handling of a 300 mm wafer.Likewise, handling of handling system 880 may be identical to handlingof a FOUP. The PCMD measures and records the conditions in the targetenvironment during a specified period, for example, during a particularprocess recipe. Then, the PCMD is automatically returned to the handlingsystem 880. Transfer of handling system 880 from one piece of equipmentto another may also be automated. Thus, the combination of a PCMD andhandling system 880 allows a PCMD to be delivered to its destinationwith a little human intervention, little disturbance to the productionenvironment and minimal contamination to the target environment.

Inside handling system 880, an electronics module 808 similar toelectronics module 208 (FIGS. 2A and 2B) may be mounted. The electronicsmodule 808 contains a battery, an E-coil, and a data-receiving unit. APCMD 800 may be placed adjacent to the electronics module, in thisexample the PCMD 800 is below the electronics module 808. In thisposition, it may receive RF power and RF data signals from theelectronics module. It may transmit data by LED to the electronicsmodule 808.

Handling system 880 may also include optical readers to observe the PCMD100 and determine its rotational orientation. In the prior art, wafersare rotated in a flat finder or notch finder to align them in a desiredrotational orientation. A flat finder usually rotates the wafer aboutits axis above a set of optical sensors that are directed at the edge ofthe wafer. These sensors detect the flat (or notch) of the wafer as itpasses and thus determine the rotational orientation. Subsequently,wafers may be realigned. Thus, relative motion between the wafer and thesensors is required. By using a greycode on a surface of a PCMD andhaving stationary optical readers, the rotational position of the wafermay be determined without any relative motion between the wafer and theoptical reader.

FIG. 8B shows a section of an edge of a PCMD 100 having greycode 850.Greycode provides a pattern that uniquely identifies locations at theedge of the wafer. Greycode is generally a code whereby successive wordschange by just one bit. On the wafer surface this is represented bychanges between light and dark areas created by patterning a depositedlayer. A word may be read along a radius such as A–A′ or B–B′. The wordread at A–A′ would be 1,1,1,0, and at B–B′ would be 1,0,1,1, where lightrepresents 1 and dark represents 0. This example uses a word of fourbits. Using a word of 8 or 9 bits allows better resolution because alarger number of uniquely identified locations are possible. Forexample, with 8 bits, 256 different uniquely identified locations arepossible. A reader, such as a linear array is used to determine theunique word at the location of the reader and also the position of theedge of the wafer. With two such readers, the rotational orientation ofthe wafer and the position of the center of the wafer may be found. Thegreycode may be located outside the area of the PCMD where the sensorsare located so that sensors do not impinge on the greycode area and thegreycode does not affect the sensors. Alternatively, where sensorsimpinge on the greycode area, the readers may be located so that atleast one reader will be able to read the greycode. For example, wheresensors are spaced 60 degrees apart near the edge of a PCMD, the readersmay be spaced 90 degrees apart so that if one reader is aligned with asensor then the other reader will have a clear reading. Both readersshould still read the position of the edge of the PCMD so that theposition of the center of the PCMD may be determined.

While rotation of a PCMD is not required to determine rotationalorientation where a greycode is used, movement of a PCMD may bedesirable for other reasons. Inductive coupling between PCMD 800 andelectronics module 808 improves as the distance between them decreases.Improved alignment between the position of the center of PCMD 800 andelectronics module 808 may also improve coupling. If the coupling isimproved, energy transfer is more rapid and the time to recharge PCMD800 may be reduced accordingly. Communication may also be improved whenPCMD 800 is correctly placed. Thus, moving PCMD 800 to the optimumposition relative to electronics module 808 may be of value. Rotation ofPCMD 800 may be desirable so that a particular rotational orientation ofPCMD 800 may be selected. Typically, maintaining the same orientationfrom one survey to another will be desirable. In this way, data from onesurvey may be accurately compared with data from another survey asindividual sensors collect data at the same locations each time. It maybe necessary to rotate PCMD 800 for alignment with process chamberelements such as positioning of specific PCMD sensors over heating zonesto correlate PCMD temperature profiles with heater zones. Sometimes, itis desirable to change the rotational orientation of a PCMD betweensurveys. A PCMD may have some inherent nonuniformity due to variationbetween individual sensors. Performing multiple surveys with differentPCMD orientations allows the effects of such nonuniformity to be reducedor eliminated. For example, a PCMD may perform surveys at a firstorientation, then at 90 degrees, 180 degrees and 270 degrees offset fromthe first orientation. The data from these surveys may then be averagedto provide a more accurate result.

FIG. 8C shows an alignment module 881 that can move a PCMD within ahandling system such as handling system 880. Alignment module 881includes a base structure 884 that forms a rigid platform for mountingother components. Base structure 884 is designed to fit in a slot withina handling system. For example, where handling system 880 is sized for300 mm silicon wafers, base structure 884 may be a disk with a diameterof approximately 300 mm. However, base structure may be thicker than asilicon wafer because it does not need to be moved in or out of a slot.Base structure 884 may be made of a strong, rigid material such as ametal or plastic.

A housing 887 is mounted to the upper surface of base structure 884.Extending from the upper surface of housing 887 are a rotation stage 883and an arm 888. Housing 887 may provide some support for rotation stage883 and arm 888 and also provides some containment for any particlesproduced by moving parts enclosed within housing 887.

Arm 888 is a movable part that can be retracted into housing 887 orextended so that it protrudes from housing 887. Arm 888 may be moved byan electric motor in response to a command signal from an electronicsmodule. At the end of arm 888 is a belt 882. Belt 882 passes around awheel or bearing so that it may rotate around the end of arm 888.Alternatively, a wheel alone may be used instead of belt 882. In anotherexample, instead of a pivoting arm such as arm 888, a post may be used.Such a post moves vertically with a wheel or belt extending from itsupper surface. Alternatively, PCMD 800 may be raised and supported bywheels around its perimeter. The wheels pushing up on the waferperimeter can raise PCMD 800 so it is floating above the FOUP orcassette ledge. By rotating the wheels, PCMD 800 can be centered bydriving it into the V-shaped slot and then retracting it back aspecified distance. PCMD 800 can then be rotated to the desiredrotational angle.

Rotation stage 883 is a disk that protrudes above the upper surface ofhousing 887. Rotation stage 883 may be rotated and may also be extendedin the vertical direction. Rotation is possible in both the raised andlowered position but is typically performed in the raised position.

A robot blade detector 886 is mounted to base structure 884. Robot bladedetector 886 may be an optical detector that can detect the presence ofan object in its field of view. Robot blade detector 886 is located sothat its field of view is placed where a robot blade from a host systemmay extend.

FIGS. 8D and 8E show alignment module 881 located within handling system880. Base structure 884 extends into a slot in handling system 880 tosupport alignment module 881. Base structure 884 may be fixed in thisposition to provide a stable platform. Electronics module 808 is locatedabove alignment module 881. PCMD 800 is between alignment module 881 andelectronics module 808. FIG. 8D shows PCMD 800 in its normal position.The edges of PCMD 800 are resting on shelves provided within handlingsystem 880. FIG. 8E shows PCMD 800 in a raised position. In thisposition it is closer to electronics module 808 so that coupling of RFpower between electronics module 808 and PCMD 800 is improved. PCMD 800is raised to this position by rotation stage 883.

FIGS. 8F–8H show alignment module 881 aligning PCMD 800. Each of FIGS.8F–8H shows two perspectives. The left view is from above and to oneside. The right view is a corresponding cross-sectional view. FIG. 8Fshows PCMD 800 positioned above alignment module 881. PCMD 800 is heldat its edges as in FIG. 8D. Arm 888 is retracted and is therefore notvisible in this view. Rotation stage 883 is clear of PCMD 800. PCMD 800may not be centered correctly at this point. This means that the centerof PCMD 800 may not be directly under the center of an electronicsmodule. Also, PCMD 800 may not have the desired rotational orientation.Either linear or rotational misalignment of PCMD 800 may be detected bygreycode readers as described above. In order to obtain an accurate mapof conditions measured by PCMD 800 the positions of the sensors on PCMD800 must be known. Thus, any map generated assumes a certain rotationalorientation. It is generally desirable that PCMD 800 be returned to thisorientation if any change occurs.

FIG. 8G shows arm 888 in the raised position. With arm 888 in thisposition, belt 882 contacts the underside of PCMD 800. Belt 882 engagesthe underside of PCMD 800 and drags PCMD 800 in the direction indicated.In a handling system this direction corresponds to dragging the PCMDdeeper into its slot. Therefore, the travel of PCMD 800 is limited bythe physical limits of the slot. Belt 882 may be a belt that is turnedby motor and that has a surface that provides sufficient traction todrag PCMD 800.

FIG. 8H shows alignment module 881 with arm 888 in the retractedposition (out of sight) and rotation stage 883 in a raised position.PCMD 800 is supported by rotation stage 883. PCMD 800 is clear of otherparts of the handling system at this point. PCMD 800 may be rotated byrotation stage 883 until it reaches a desired orientation. PCMD 800 mayremain in a raised position for recharging from electronics module 808.When recharging is complete, rotation stage 883 may be lowered and PCMD800 may be returned to its normal position where it may be picked up bya robot blade that extends under it and lifts it from its slot

Robot blade detector 886 ensures that alignment module 881 does notattempt to engage PCMD 800 while the robot blade is extended under PCMD800. If alignment module 881 tried to engage at such a time, damagecould occur to PCMD 800, alignment module 881 or the robot blade. Toprevent this alignment module 881 may have an interlocking mechanism toprevent it from operating when robot blade detector 886 detects thepresence of a robot blade.

After data is collected by a PCMD and transferred to a handling system,the data may still need to be transferred to a point where it can beaccessed by an end-user. This may be done in a variety of ways, two ofwhich are shown in FIGS. 9A and 9B. For example, the end-user 985 mayaccess the data collected by PCMD 900 by using a laptop computerconnected to the handling system by a USB cable, IRDA connection, Wi-Fior Bluetooth wireless connection, or by use of other technologies. Thehandling system 980 may connect to a network, such as by an Ethernetconnection, to allow the end-user to receive data on a PC at anotherlocation. A PDA may be used instead of a PC for receiving and viewingdata. Alternatively, the data may be recorded on a flash memory card andphysically moved to a laptop, PDA or other device. A softwareapplication 987 processes the data sent by the handling system 980 toprovide data to end-user 985 in a format that is appropriate. Forexample, digital data may be converted into temperature readings.Software application 987 may run on a variety of platforms includinglaptop PC, desktop PC or PDA.

In one embodiment, the transfer of data from handling system 980 isachieved by using an active RFID transmitter in handling system 980.This takes advantage of the presence of an RFID reader close to the FOUPto transmit data to a network where it may be accessed by an end-user.Semiconductor facilities (Fabs) that use FOUPs generally track theindividual FOUPs and their contents by means of RFID tags. Tags aregenerally passive devices capable of providing an identification numberwhen they are interrogated by a reader. A reader is generally providedat the load port where a FOUP connects to a processing system so thatthe identity of the FOUP at the load port at any particular time isknown. A network of such readers throughout the Fab are connected to asoftware system that can monitor the position of different FOUPS andcoordinate the movement of FOUPs to optimize efficiency. Certainindustry standards regarding such a network are detailed in “Generalmodel for communications and control of manufacturing equipment,” (GEM),SEMI E30 and SEMI E87-0703. The presence of such a reader connected to anetwork provides a convenient way to transfer data from a handlingsystem to an end-user.

An active RFID transmitter may be used to send recorded data and otherinformation from a handling system to a reader. The network may beconfigured to process data in packets corresponding in size to theidentification number for a FOUP, typically 80 bytes. In this case, theinformation from handling system may need to be sent in a series of 80byte chunks. Using an RFID system for this purpose has the advantagethat the receiving hardware already exists at the desired location andis connected to a network, the transmission is over a very short rangeand thus requires very little power and does not generally suffer frominterference from neighboring systems. Three types of RFID are at thistime commonly used, a low frequency system at a frequency of 125 kHzthat has a range of less than 12 inches, a medium frequency systemoperating at 13.56 MHz that has a range of about 90 feet and a highfrequency system with a frequency of 2.4 GHz and a range in excess of100 feet. Any of these may be used for sending data according to thisinvention. Active RFID transmitters may transmit in 3-dimensions so thatthe alignment of the transmitter and reader are not critical. Oneexample of such a transmitter is an ECM electronics 3DC1515. While theabove example refers to FOUP technology used with 300 mm wafers, thisaspect of the invention may also be used with other industry standardsubstrates and substrate carriers such as 200 mm wafers and SMIF(standard mechanical interface). Similar industry standards exist forother substrates and carrier.

In the system illustrated in FIG. 9A, the end-user in the fabricationfacility manually initiates one or more of data transfer from thehandling system 980, loading into and unloading the PCMD 900 from thehandling system 980, and the like. Consistent with the trend forfabrication facilities to become more computer controlled with little orno intervention by a facility engineer or other end user, communicationwith the handling system 980 may be made automatic, such as illustratedin FIG. 9B. Measurement and other data and commands are transmittedbetween the handling system 980 and a computer 983 by one of Bluetooth,WAN, IRDA or RFID, or others, as described above with respect to FIG.9A. The computer 983 operates according to application software 981 tocontrol operation of and transfer of data with the handling system 980and PCMD 900. The computer 983 is preferably connected to a centralcomputer system through an interface 984, according to the SECSII, GEMor other appropriate bus standard.

A charger 982 of the batteries within the handling system 980 preferablyincludes a split transformer, also commonly known as an inductive powercoupling device, that allows connection of charging power without theneed for a solid mechanical or electrical connection of the power sourcewith the handling system. The portion of the split transformer that isconnected with the handling system 980 is preferably attached to anoutside surface thereof. The mating portion of the split transformer isheld fixed in a location where it is abutted by the handling systemportion when the handling system 980 is placed in a particular definedlocation. This allows battery charging to automatically take place whenso positioned by the robotic machinery operating the tool or the portionof the fabrication facility in which the PCMD system is being utilized.

FIG. 2B shows the front or user side of HS 200. A memory card 228 isshown inserted into electronics module 208 and may be considered part ofHS 200. HS 200 accommodates any number of memory card formats such asbut not limited to the smartcard®, Sony memory stick®, the SecureDigital (“SD”) card®, Compact Flash (“CF”), or Multi-Media Card®(“MMC”). A PCMD is sent out “on a survey” to record the variousconditions in different types of environments. For each environment andfor the entire survey, it may be desirable to alter various parametersof the PCMD such as the sampling rate, sampling duration, and thesensors used. Display 232 quickly conveys information to a userregarding the setup of the PCMD such as the number and arrangement ofsensors to be used in a survey, the length and times of the variouscycles of a survey, and the sampling rate of the sensors and sensorelectronics etc. A survey profile and the data retrieved on the surveymay also be stored on the memory card 228 or within flash memory ofelectronics module 208.

All the parameters of PCMD 100 and HS 200 may also be accessed andconfigured by a personal computer or other smart device thatcommunicates via a universal serial bus (USB) of port 224 or via aninfrared port 220. They may also be accessed by a remote controlcommunicating to infrared port 220. HS 200 and the PCMDs may also beconfigured and the data gathered may be manipulated with the functionswitches 240 that are software driven and control/access the most oftenused parameters of a PCMD. Indicator lamps 232 also serve to inform theuser of the condition of HS 200 and the PCMDs within HS 200. Viewport244 allows a user to view one or more of the PCMDs.

FIGS. 3A and 3B are cross sections of embodiments of PCMD 100 (withoutthe components) that will be referenced by the flowcharts of FIGS. 4Aand 4B, respectively. The cross sections and flow charts, describing howthe PCMDs are made, should be viewed in tandem.

FIG. 4A describes the process of making an embodiment with a singleconductive layer used for the circuit traces. In step 404 of FIG. 4A,insulating layer 304 is formed upon substrate 102. Insulating layer 304preferably comprises an oxide, but may be any well known insulatingmaterial, and may be deposited or grown upon the surface of substrate102. In step 408, insulating layer 308 is formed upon insulating layer304. Insulating layer 304 and 308 preferably, but not necessarily,comprise different materials. In the preferred embodiment, insulatinglayer 308 comprises a nitride. In step 412, a conductive layer 312 isformed upon insulating layer 308. Next, in step 416, electrical tracesare patterned and etched in conductive layer 312 according to well knownpatterning and etching methods. In step 420, passivation layer 316 isformed upon the conductive traces of step 416. In step 424, cavities 142for components 140 are formed within the substrate through one or moreof the layers. The cavities 142 may be mechanically formed or may beetched. In step 428, components 140 (not shown) are inserted withincavities 142 and electrically coupled to the traces in conductive layer312, seen in FIG. 1C. Next, in step 432, a passivation layer (not shown)is formed over components 140 and the other layers. The passivationlayer may comprise any well-known materials, but preferably comprisespolyimide or oxynitride. Optionally, step 436 may be performed, in whichan electrical and chemical protective shield layer is formed over thepassivation layer. This is especially useful in protecting the PCMD fromvery harsh processing environments such as in plasma etch chambers, asthe shield layer is nearly impermeable to the gases and other elementscommon to such environments. The shield layer should also be resistantto the etching process induced by high energy ion bombardment in plasmachambers. One example of a shield layer is actually a composite ofdifferent layers, including a polymer layer such as Mylar®, a PE layer,a metallic foil, and a sealant layer such as surlyn®. The totalthickness of the shield layer may range from 25 to greater than 99microns.

FIG. 4B describes the process of making an embodiment with twoconductive layers coupled by inter-level vias. Steps 404 and 408 are thesame as those in FIG. 4A. In step 412, the first conductive layer 312Ais formed on insulating layer 304. In step 413, a dielectric layer 310is formed upon conductive layer 312A. After that, openings for vias 312Care formed in dielectric layer 310 in step 414. Next, in step 415,conductive layer 312B and vias 312C are formed on/in the dielectriclayer 310. In step 416 electrical traces are patterned and etched in theexposed portion of conductive layers 312A and 312B. Steps 420–436 arethe same as in FIG. 4A.

FIGS. 10A and 10B show examples of lids 1010–1013 protecting components1020–1022 of the PCMD from the environment. In FIG. 10A, a single lid isused for three components. The number of components covered by a singlelid depends on the sizes and locations of the components but may beanything from one component to all the components in the PCMD. FIG. 10Ashows three components 1020–1022 and the attached wire bonds 1048covered by a single lid 1010. In FIG. 10B separate lids 1011–1013 areused for each component 1020–1022. Various materials may be used to formlids such as lids 1010–1013. For example, a ceramic lid similar to thatused for packaging integrated circuits may be adapted to cover acomponent or group of components in a PCMD. For particularly harshchemical environments lids may be made from materials such as sapphirethat resist chemical attack. Where protection from electromagneticfields is required, lids may be made of conductive material such asmetal or doped silicon. For some applications, plastic lids may be used.Lids 1010–1013 are bonded to the substrate 1002 in a conventionalmanner.

In the example of FIG. 10C, a single lid 1030 is used to cover the uppersurface of the substrate 1002. Lid 1030 may be made of the same materialas substrate 1002. For example, where the substrate is made of silicon,the lid may also be made of silicon. Thus, PCMD 1000 resembles a siliconwafer from the outside. Its appearance and characteristics are similarto those of a silicon wafer so that the measured values are as close aspossible to the values that would be found in a silicon wafer. The lid1030 may be bonded to substrate 1002 to form a sealed unit. Cavitieswithin such a unit may be filled with a suitable material to exclude gasthat might expand at high temperature and cause the unit to fail.

In the example shown in FIG. 10D, a three layer structure is used.Traces (not shown) may be formed and components 1020–1022 may beattached to substrate 1002 and bonded to the traces. Then, a secondlayer 1050 is put in place. This layer has cut-outs formed for thecomponents 1020–1022. This layer may be silicon so that it has similarcharacteristics to the substrate 1002. Next, a lid 1030 is attached tothe upper surface of layer 1050. This method allows cavities to beuniform in depth because the depth of each cavity is equal to thethickness of layer 1050. Also, the upper and lower surfaces of layer1050 may be highly planar providing good attachment to substrate 1002and lid 1030.

In the embodiments of FIGS. 10A–D, the integrated circuit die arepreferably attached to the substrate in the manner described above withrespect to FIG. 1C, and the thermally conductive potting material mayalso fill the cavities to protect the delicate lead wires and avoidcreation of thermal voids across the substrate 1002.

An alternative structure of the PCMD to that described above isillustrated in FIGS. 11A and 11B. The sensor, processor and otherintegrated circuits and electronic components are positioned in enclosedcavities within the substrate. The cavities are preferably formed in asurface of one of top and bottom discs of silicon or other material thatare attached together with a thermal and electrical bond to form thefinished substrate. The electronic components are connected together byconductors encapsulated within a thin polymer film that is sandwichedbetween the discs. This film extends its conductors between thecomponents in a manner to cover only a small portion of the area of thediscs, therefore minimizing any disturbance of the thermalcharacteristics of the resulting measuring instrument. The thermalcharacteristics remain very close to those of a solid disc.

Referring to FIG. 11A, a circular wafer is shown in plan view. Onlyfifteen temperature sensors 1301–1315 are shown for simplicity ofexplanation, many more usually being desired for a typical test wafer.Strips of polymer film containing electrical conductors extend betweensensors attached to them and one of two half-circle polymer filmsegments 1317 and 1319 that contain an interconnecting bus therein. Filmstrips 1321–1323 extend in straight radial lines and each have twosensors attached, and film strips 1325–1327 are “Y” shaped with threesensors attached to each. Another polymer film segment 1331 positionedbetween the two bus segments 1317 and 1319 includes the micro-controllerand associated electronic components attached to it. The sensors andfilm strips and segments are contained within the substrate, mostconveniently mounted between top and bottom plates having the same outerdimensions. The film segment 1331 extends to another polymer segment1332 that connects with an external center coil 1333 and foursurrounding LEDs 1334 on the top exposed surface. Batteries 1343 and1345 are electrically connected to the bus in respective half-circleportions 1317 and 1319. There may alternatively be only one battery ormore than two batteries installed, depending upon the application andresulting power needs. The sensors, electronic components and powersource are thus connected together into a system described elsewhereherein (such as by FIG. 18 hereinafter) by the conductors in the polymerfilm segments within the substrate structure. The polymer utilized ispreferably polyimide.

The batteries 1343 and 1345 can be mounted on the top surface of thesubstrate but are preferably also contained within the substrate. Aclosable opening (not shown) is then provided in one of the plates overeach of the batteries for access to replace them during the life of theinstrument. It is preferred that both sides of the completed substratebe smooth without any components mounted on these surfaces except thatit is necessary in this embodiment for the coil 1333 and LEDs 1334 to beexternally mounted.

Referring to the cross-sectional view taken along the polymer strip1321, shown in FIG. 11B, cavities 1335 and 1337 are formed in a bottomdisc 1339 to contain the respective temperature sensors 1301 and 1302.These temperature sensors are pre-attached to the polymer strip 1321 anddirectly electrically and mechanically connected to the conductorstherein without the use of bond wires. Indeed, the straight polymerstrips 1321–1323 are the same, as are each of the “Y” strips 1325–1327,which greatly simplifies manufacturing. Only a limited number ofdifferent polymer segment structures need to be made. In thisembodiment, only two different sensor assemblies are used plus theelectronic component assembly 1331 and the segment 1332 for the coil1333 and LEDs 1334. In each of these, the components are attached to thepolymer segments before installation as a pre-assembled unit intogrooves provided in the top surface of the bottom disc 1339 for thepolymer to extend between the cavities containing the sensors and othercomponents. The sensors and other components on the individual polymersegments can even be tested and calibrated before installation. Once allthe polymer segments are installed in the bottom disc 1339, a top disc1341 of the same outside shape is then attached to the bottom disc, thecombination forming the completed substrate. Alternatively, the groovesfor the film strips and segments may be formed on the bottom surface ofthe top disc 1341. A more complicated layout having many more sensors isimplemented in the same manner, although there may be one or a fewadditional different polymer segment shapes with sensors and/or othercomponents attached.

The sensors and other components are preferably attached to the bottomof the disc cavities, as illustrated in FIG. 11B where the temperaturesensing chips 1301 and 1302 are attached to the bottoms of respectivecavities 1335 and 1337. Any space around the sensors and componentswithin their cavities are also preferably filled with thermallyconductive material. The adhesive and fill materials can be the same asdescribed above with respect to FIG. 1C. Since the polymer strips andother segments cover only a small portion of the area of the resultingmeasuring device, the top and bottom discs 1339 and 1341 are firmlymechanically, thermally and electrically attached with an appropriateadhesive over nearly all of the area of the two discs, preferably morethan eighty percent or even ninety percent of their common area. In thisexample, the bottom and top discs are circular with the same diameter.

As a result of these features, the sensors, electronic components,conductors, polymer and other elements within the disc perturb thetemperatures measured across the wafer very little. Because of theprotection provided the electrical elements by the structure of FIGS.11A and 11B, the device may be used to measure temperatures a variety ofhostile environments such as in plasma, wet and plating processes, aswell as for tuning a photoresist process hot plate. Of course, theinstrument is not limited to these specific applications. Nor is theconfiguration illustrated in FIGS. 11A and 11B limited to themeasurement of temperature, as sensors of other parameters that can bemeasured from within the structure may be substituted for thetemperature sensors. And in most any application, the instrument can beinverted when used, the top and bottom discs being reversed.

In an alternative embodiment, instead of raising PCMD 800 to move itcloser to the electronics module, the electronics module or a portion ofthe electronics module is lowered to bring it closer to PCMD 800. FIG.8I shows a portion of an electronics module that contains E-coil 810being lowered towards PCMD 800. As the distance between E-coil 810 andPCMD 800 decreases, the efficiency of power transfer from E-coil 810 toPCMD 800 improves. Typically, when E-coil is close to PCMD 800, the timeto recharge PCMD 800 is about ten minutes.

When robot blade detector 886 detects a robot blade approaching PCMD800, moving parts that might interfere with the robot blade must beplaced in positions where they do not interfere. Where E-coil 810 islowered to improve coupling with PCMD 800, it must be retracted beforethe robot blade attempts to lift PCMD 800. Typically, this means that itmust be retracted within 0.1–0.3 seconds from the time that a robotblade is detected by robot blade detector 886.

In one embodiment, the position of the FOUP door may determine theposition of E-coil 810. When the FOUP door is open, the robot mayattempt to pick up a PCMD, so E-coil 810 is kept in the raised position.When the FOUP door is closed, the robot will not attempt to pick up thePCMD, so E-coil 810 is placed in the lowered position. The movement ofE-coil 810 may be triggered or powered by the movement of the FOUP door.Alternatively, the movement may be powered by a motor or a spring.Linking E-coil motion to the FOUP door motion may make robot bladedetector 886 unnecessary.

A compression algorithm is utilized for the multiple channels of data.The algorithm may use both spatial and temporal compression. It issuitable for signals with small temporal motion and uses an adaptivecompression that depends upon signal shape and environment. It comprisesthree steps: 1) analyzes spatial temperature distribution; 2) analyzestemporal distribution; 3) analyzes temperature profile andcharacteristics; and 4) compresses or omits certain data based upondifferences across the wafer detected in the above steps.

FIGS. 12–15 illustrate examples of the data compression. Referringinitially to FIG. 12, use of the microcontroller 124 (FIG. 1) to processdata from the sensors 124 is conceptually illustrated. There are manycommercially available microcontrollers that can be employed for thisapplication. One of the MSP430 mixed signal series of microcontrollersavailable from Texas Instruments Incorporated is one good choice. Thismicrocontroller includes an analog-to-digital converter 1101 andnon-volatile flash memory 1103, as well as a central processing unit1105, volatile random access memory 107 and an input-output interface1109. The analog outputs of the sensors 124 are sampled one at a time,as indicated by a switching circuit 1111, and converted into a digitalsignal. The sample rate, namely the setting of the time interval betweensamples of the sensors outputs, is controlled by a timer 1102 through acontrol circuit 1113, and may be varied to further reduce the amount ofstored data in a manner described below.

The digital sample values at the output of the ADC 1101 contain a numberof bits that can represent the values measured by the sensors with thefull resolution that is desired of the system. In an example algorithm,these values are then compressed to values of incremental differencesbetween sensor readings, either temporally (differences between timesequential values detected the same sensors) or spatially (differencesbetween different sensors at the same sample period). The incrementaldifferences are expressed with a far fewer number of bits than thevalues initially acquired with full resolution. This allows the size ofthe non-volatile memory on the wafer, or the bandwidth of transmissionof the data from the wafer, or both, to be minimized. The amount ofbattery power used to acquire and store and/or transmit the data isreduced as a result.

The flowchart of FIG. 13 provides an outline of an example compressionalgorithm. In a first step 1113, a set of data samples is acquired fromsensors 124 at the output of the ADC 1101 (FIG. 12) with the fullresolution. This acquisition takes place a “set interval” after valuesfrom the same sensors were taken the last time. This interval can beindependently controlled, as described below. These data are temporarilystored in the RAM 1107 with the full number of bits, as indicated by astep 1115.

In a next step 1117, a difference between the value just read from agiven one of the sensors 124 and the value read during the immediatelypreceding cycle for the same sensor is calculated by the CPU 1105. Thisis done for all the sensors being read and these temporal differencesare temporarily stored in the RAM 1107. Similarly, in a next step 1119,differences between the values of the individual sensors being read andone of sensors designated as a reference, all for the present sampleperiod, are calculated and temporarily stored as spatial differences.The stored temporal and spatial differences are then compared in a step1121 to identify which set of differences are the least. These lesservalues are selected for non-volatile storage on the wafer and/ortransmission from the wafer to represent the current period output ofthe sensors with the least amount of data. In one of steps 1123 or 1125,the selected set of difference values is stored. The selected set ofdifferences can be written into the flash memory 1103 in each period orcan be accumulated in the RAM 1107 until a block of data exists thatmakes it more efficient to program together as a block into the flashmemory.

An example table of this difference data obtained during many sampleperiods is given in FIG. 14 to further illustrate this process. At thebeginning of a measurement cycle, in the first data sample period, thevalues of all the sensor outputs are stored in an uncompressed “full”form in the column marked “start”. This provides an absolute referencefrom which temporal differences are calculated and the absolute valuesreconstructed off the wafer during decompression. Similarly,uncompressed data is stored for one of the sensors in each of the sampleperiods, shown to be sensor 0 in FIG. 14, as an absolute reference fromwhich the spatial differences are calculated and the absolute valueslater reconstructed.

In a sample period at time (t-n1), a difference is stored for eachsensor between the current sensor reading and that of the immediatelypreceding sample period, a temporal difference. At another sample periodat time (t-n2), a difference is stored for each sensor between itscurrent value and that of the reference sensor 0, a spatial difference.And at the final time period represented in the example of FIG. 14,temporal differences are again calculated and stored to represent thevalues of the sensor outputs at that time. It may be desirable to limitthe frequency of switching between storing temporal or spatialdifferences by establishing some threshold difference between them toexist before a switch is allowed. Although certain samples are stored astemporal differences and others as spatial differences, their fullvalues can all be reconstructed by a personal computer of othercomputing device that receives this data, either in real time or afterthe test is concluded, from the data of the table of FIG. 14.

Periods when temporal or spatial differences may be preferred can beillustrated by the temperature curve of FIG. 15, which roughlyrepresents the temperature cycle in a photoresist process that rapidlyheats the wafer (region 1127), holds a maximum period for a time (region1129) and then rapidly cools the wafer (region 1131). In the regions1127 and 1131, the temporal differences are likely greater in magnitudethan the spatial temperature differences, assuming the usual goal tomaintain the temperature across the wafer substantially uniform. Thespatial differences can then be represented by a fewer number of bits ofdata so will be chosen. In the region 1129, temporal differences mayresult in the least amount of data to be stored.

Although automatic selection of the most advantageous of the temporal orspatial differences at each measurement cycle has been described, theprocess could alternatively be implemented by causing one or the otherto be used throughout various portions or all of a given measurementoperation, either automatically or by user selection. Useful datacompression can also be obtained by a system that calculates only one ofthe temporal or the spatial differences. One of the steps 1117 and 1119of FIG. 13 is then omitted, as is also the step 1121 and one of thesteps 1123 and 1125.

Returning to the flowchart of FIG. 13, additional data reduction canoptionally take place by controlling the rate of data acquisition, the“set interval” between the taking of successive samples of sensor data.In a first step 1133 of an example process, it is determined whether theset interval should be changed on account of the current absolute valueof temperature or other parameter being measured. For example, in FIG.15, it may be unnecessary to know much about the temperature when belowsome threshold 1135. In this case, the set interval can be lengthenedand thus reduce the amount of data that is acquired and stored. When thetemperature is above the threshold 1135, in this example, the shorterset interval is used. This feature will usually be implemented by theuser setting such a threshold temperature. Further, more than two setintervals can be provided, each operable within a unique one of morethan two temperature ranges. And the two or more temperature ranges maybe defined differently, depending upon whether the temperature is risingor falling. Or some criterion other than absolute temperature, either asdesignated by the user or predetermined, may be used to cause the setinterval to change. This all depends upon the application to which thewafer is put.

So if, in the step 1133, it is determined that a predeterminedcondition, such as a particular absolute temperature range, exists thatcalls for a change of the set interval from that used in the justcompleted acquisition and compression operation, the change is made in astep 1135 and the process returns to the step 1113. It is then repeatedwith the new set interval for acquiring data samples. An advantage ofincreasing the set interval whenever possible is that the ADC 1101 andassociated components are used less often and thus the wafer batterypower consumed by them is reduced.

But if, in the step 1133, it is determined that no such predeterminedcondition exists, the processing may proceed to a step 1137 where theset interval may be changed in response to a change in therate-of-change (slope) of the measured temperature or other parameter.The processing then returns to the step 1113 where a new set of data isacquired and compressed with the changed set interval. Usually, if theslope is great, the set interval is desirably made small, while in thecase of a near zero rate-of-change, the set interval can be lengthenedwithout losing any valuable data. The measured temporal differencesdisclose whether the temperature or other parameter being measured ischanging rapidly or not. When on the slopes 1127 and 1131 of the curveof FIG. 15, the set interval can be made short, while when on the flatportion 1129, it can be considerably lengthened.

It is of course desirable that the test wafer be able to gather andstore data for the entire duration (runtime) of the processing operationbeing monitored. Since it is also desirable to minimize the number andsize of the onboard batteries 112 (FIG. 1A), the efficient use ofbattery power is important. Increasing the set interval between storageof data samples saves power. This and the further data compression alsoreduce the amount of non-volatile memory of the microcontroller that isnecessary to store the data acquired throughout the processing runtime.It is also desired to minimize the amount of such memory that isnecessary to include on the test wafer.

Reference to FIGS. 16A–16D will now be made to describe another waferhandling system embodiment that is a modification of the systemsdescribed above with respect to the two wafer handling systems of FIGS.2A–2B and FIGS. 8A and 8E–8I. Additional and alternative features andstructural elements are included. The use of a carrier 1151 for storingand transporting a PCMD 1153, and the techniques for doing so, aresubstantially the same, however.

An electronics module 1155 is mounted in the carrier 1151. The PCMD 1153need not be moved up and down in this embodiment, and is placed within astorage slot a small distance below the electronics module 1155. Butrather than being supported by the carrier slot, the weight of the PCMD1153 rests on several wheels, in this example four wheels 1157–1160,which are carried by structures 1163 and 1165 attached to at leastopposite interior walls of the carrier 1151 below the slot designated toreceive the PCMD 1153. The outside surfaces of the wheels that arecontacted by the PCMD 1153 are preferably padded so as not to causedamage to the PCMD and which frictionally engage the underside of thePCMD in order to rotate it. The wheels 1157–1160 are rotated about theiraxes by respective individual electrical synchronous motors 1167–1170.The wheels 1157–1160 are confined to rotate about axes that pass througha point that is to be coincident with a center 1173 of the PCMD 1153placed within the carrier, as indicated by the dashed lines of FIG. 16D.Fewer or more wheels can be used, and/or can be positioned withdifferent radial spacings around the PCMD, so long as the PCMD issupported with stability in a flat position within the carrier.

Another difference from the earlier described carrier embodiments is themechanism for charging the batteries on the PCMD 1153 when positioned asshown. Rather than moving the wafer up to the bottom of the electronicsmodule 1155, or the module 1155 down to the wafer, an inductive chargingcoil 1175 is attached to a bottom surface of a strip 1177 of flexiblematerial, preferably a plastic such as a polyimide about one mil. thick.As best illustrated in FIG. 16B, the strip 1177 is attached at an end1179 to the underside of the module 1155 at either the front or the backof the carrier 1151. The opposite end of the strip is attached to an arm1181 of a solenoid 1183 that is attached to the underside of the module1155 at the other of the front or rear of the carrier 1151. In oneposition of the solenoid arm 1181, that of FIGS. 16B and 16C, the strip1177 is lowered so that its coil 1175 rests on a center coil 708 (fromthe embodiment of FIG. 7) of the PCMD 1153. In the other position of thesolenoid arm 1181, the strip 1177 is pulled upward toward the undersideof the module 1155, as shown in a dashed line of FIG. 16B and in FIG.16A. In this position, the PCMD 1153 may be inserted or removed by thefacility's robot.

An advantage of placing the charging coil on the flexible strip 1177 isthat little or no magnetic core material needs to be included. This isbecause the charging coil 1175 is allowed to rest directly on the coil708 of the PCMD 1153. This provides very good magnetic coupling betweenthe two coils. The strip 1177 and coil 1175 do not harm the PCMD or itscoil 708 because of the resulting light weight of the structure.

The PCMD 1153 includes the four light emitting diodes (LEDs) 728–731 ofthe PCMD embodiment of FIG. 7. Data is transmitted from the PCMD 1153 tothe electronics module 1155 through these LEDs. A single photodetector1185 is positioned on the underside of the module 1155 to receive thesignal emitted by the selected one of the LEDs 728–731 on the PCMD whenin the position shown in FIG. 16A. The photodetector 1185 is displacedfrom the center 1173 of the PCMD when resting in the carrier 1151 as arethe LEDs 728–731 on PCMD 1153. More than one photodetector could be usedbut the use of only one is preferred.

Also included on the underside of the module 1155 are two line cameras1187 and 1189 to provide one-dimensional data, along with respectivelight sources 1191 and 1193. The cameras are positioned to image twoportions of an visual rotation position code included around the outsideof the PCMD, and the light sources are positioned to illuminate thoseportions being imaged. Such a code is not shown in FIGS. 16A–16D but itmay be the graycode 150 of the PCMD illustrated in FIG. 1D. Dataobtained by two cameras radially displaced from each other around thecircumference of the PCMD allows the rotational position of the PCMD tobe determined and, if less than 180 degrees apart, to determine thecenter of the PCMD. For peripheral position encoding such as thegraycode 150 (FIG. 1D), the cameras 1187 and 1189 may be positionedabout 137 degrees apart from each other.

The module 1155 (FIG. 16A) contains the electronics necessary tocommunicate with the PCMD 1153, monitor the state of and charge itsbatteries and perform other functions without having to make a wireconnection with the PCMD. These electronics are also battery powered,since the carrier 1151 needs to be portable and is usually moved withina processing facility by a robot. Adequately sized batteries can beincluded within the relatively large module 1155 but are preferablymounted externally of the carrier 1151 such as on an outside surfacethereof. An example of such an electronic system is illustrated by theblock diagram of FIG. 17.

A single integrated circuit microcontroller chip 1201 and one or moreflash memory chips 1203 are included on a printed circuit board (notshown) installed in the module 1155. One use of the non-volatile memory1203 is to store data earlier acquired and stored on the PCMD 1153. Thisdata is transferred from the PCMD by infrared signal transmission, inthe example being described, such as described above with respect toFIGS. 7 and 16A–16D. Data from the photodetector 1185 is directed by thecontroller 1201 to the memory 1203. These data are removed from themodule 1155 by any of several methods. One is by loading the data onto aflash memory card 1205 that is removable inserted into a card receptacleprovided in the module 1155 (not shown). The controller 1201 directs thedata to the memory card 1205 through an interface circuit 1207. Anothermethod of exporting data is through an Universal Serial Bus (USB)interface, which is schematically shown in FIG. 17 by a USB receptaclethat physically is placed on the outside of the module 1155 (not shown)and a USB transceiver 1211 on the circuit board within the module 1155.Another way of obtaining the data stored in the flash memory 1203 isthrough a radio frequency transmitter 1213, which can operate accordingto a suitable existing standard such as Bluetooth or Wi-Fi.

Once exported to a personal computer or other suitable computing device,the data may be post-processed including decompressing the data. Ifcompressed according to the techniques described above with respect toFIGS. 12–15, the temporal and/or spatial data, as exists, are combinedwith those data points stored with full resolution and each other toprovide all data values with the full resolution and without any loss.

In the specific system example of FIG. 17, the primary source of poweris a rechargeable battery 1219 that supplies operating power through apower control circuit 1217 to the other components shown. Anon-rechargeable back-up battery 1215 may also be included for use incase the battery 1219 become discharged during use. In response to thevoltage from the primary battery 1219 dropping below a set threshold,the control circuits 1217 switch away from the battery 1219 and to thebattery 1215. A convenient way to recharge the battery 1219 is through aUSB connection with a personal computer or other host device, or througha non-contact power path such as the split transformer (not shown)mentioned above. While connected, such a device provides power throughthe USB receptacle 1209 to a charger 1221 that is operably connectedwith the battery 1219.

The controller 1201 also drives the PCMD rotation motors 1167–1170through a motor control circuit 1223. The battery charging coilpositioning solenoid 1183 is also controlled by the controller 1201through a driving circuit 1225. Data and battery charging energy areprovided to the coil 1175 by a radio frequency driver 1227, in responseto data and control signals from the controller 1201. Images from thecameras 1187 and 1189 are received and processed by the controller 1201,as are the associated illumination sources 1191 and 1193, which arepreferably turned on only when images are being acquired from thecameras 1187 and 1189. A standard RFID radio frequency interface 1229can also be used for transmitting data and/or receiving commands, asdescribed previously.

The system of FIG. 17 also conveniently provides user interface devices.A display 1231 can be any of a convenient display device, such as asmall LCD screen to provide status information of the control system.For the user to input commands or make inquiries, a standard keyboardcan be used but a remote control 1233 will usually be more convenientsince it can be made portable. In this case, a remote control interface1213 with the controller 1201 is provided as part of the system. Both ofthe control devices 1213 and 1233 are preferably PDAs because of theirready availability, built-in wireless communication capability andrelative ease with which they may be adapted to this application.

A block diagram of the circuits carried by a typical PCMD beingdescribed is given in FIG. 18. The microcontroller integrated circuitchip 104, previously described with respect to FIG. 12, is the heart ofthe data acquisition, storage and exporting functions of a PCMD.Although the parameter sensors may be distributed over the surface ofthe PCMD according to any number of arrangements or patterns, they areelectrically connected in a matrix of n rows and m columns. The row andcolumn connections shown in FIG. 18 are implemented by the conductivetraces formed on the surface of the PCMD. Three such rows and threecolumns are shown in FIG. 18 for simplicity of explanation but many morethan nine sensors 1241–1249 will usually be employed. More than fifty istypical, such as sixty-four sensors in a matrix of eight-by-eightsensors, or more. In the example being described, the sensors areindividual integrated circuits of the type described earlier where, inresponse to being provided power, output a voltage or current related tothe value of the parameter being measured, such as temperature.

In the example of FIG. 18, data are acquired from one column of sensorsat a time. The controller turns on power to one of the m column lines ata time, in sequence, while leaving the sensors in the remaining columnswithout power. Each sensor in the energized column then outputs itsparameter dependent voltage onto a different one of the n row lines towhich it is connected. The individual sensor voltages on the row linesare then converted into digital signals, one at a time, by ananalog-to-digital converter circuit within the controller 104, aspreviously describe with respect to FIG. 12. After the data from onecolumn of sensors are converted and stored in a memory within thecontroller 104, power to that column is turned off by the controller 104and power turned on to the next in order column line. Parameter valuesare obtained from the sensors in that column and stored in the samemanner. This continues until data has been acquired from all the sensorsin the matrix. A short time later, the process repeats to update thevalues of the parameters being sensed by the sensors across the PCMD.

Data so acquired and stored within the controller 104 are transferred tothe electronics module 1155 of the wafer carrier (FIGS. 16A and 17) byone of the LEDs 728–731 that is most closely positioned to thephotodetector 1185, as described above with respect to FIG. 7. In orderto save power and reduce the peak current that is necessary for thecontroller to provide to the LEDs, each is preferably driven by thevoltage stored in a capacitor connected to it that has been chargedthrough a resistor. Such a charging circuit is shown in FIG. 18 to beconnected to each of the LEDs 728–731. When the controller then connectsto one of the LEDs through an internal switching transistor to generatean infra-red pulse from the LED, the necessary current to do so issupplied by its capacitor discharging through the LED.

The controller 104 utilizes an external clock source 1253, a preferredclock described above with respect to FIG. 6. Power is supplied to thecontroller 104 through a voltage regulator 1255 from battery(ies) 1257attached to the PCMD. The voltage output of the battery power source1257 is monitored by the controller 104 through a level shifting circuit1259. The controller uses its analog-to-digital converter to firstconvert this analog signal to a digital value.

When the PCMD is positioned in a carrier such as shown in FIG. 16A, theelectronic system therein (FIG. 17) electromagnetically talks with thePCMD electronic system (FIG. 18) through their adjacent coils 1175 and708 (FIG. 16C). Commands, status inquiries or other communicationsreceived by the coil 708 of the PCMD are received by the controller 104(FIG. 18) through a line 1261 connected to one side of the coil. Whenthe battery 1257 is to be charged, a voltage level placed on a line 1263by the controller 104 enables a rectifier 1265 to receive the output ofthe coil 708. A d.c. output of the rectifier 1265 is then connectedacross the battery 1257.

Since the minimization of the amount of power consumed by the PCMD isquite important, as discussed in various places above, the controller104 operates to turn off its power by generating a sleep signal in aline 1267 that is connected with the voltage regulator 1255.

The embodiments described above have applications in monitoringprocessing conditions in locations other than processing chambers.Conditions experienced by wafers during transport and storage may alsoaffect the characteristics of the devices produced and therefore it maybe desirable to measure and record such conditions. For example, a PCMDmay remain in a FOUP to record conditions in the FOUP. This data may berecorded in the PCMD or may be transmitted by RFID without being stored.

While particular embodiments of the present invention and theiradvantages have been shown and described, it should be understood thatvarious changes, substitutions, and alterations can be made thereinwithout departing from the spirit and scope of the invention as definedby the appended claims. For example, the location and type of thesensors may be different than in the examples described.

1. An instrument for measuring a parameter, comprising: a substrate, aplurality of sensors carried by and distributed at positions across asurface of the substrate that individually measure the parameter atthose positions, at least one electronic processing component carried bythe substrate surface, electrical conductors extending across thesubstrate surface and connected to the plurality of sensors and said atleast one electronic processing component, wherein the sensors and saidat least one electronic component are positioned in cavities formed intothe substrate surface, and a material filling the cavities around thesensors and said at least one electronic component.
 2. The instrument ofclaim 1, additionally comprising a rigid protective cover extendingacross the substrate over at least the sensors and said at least oneelectronic component.
 3. The instrument of claim 1, wherein thesubstrate is a circularly shaped silicon wafer.
 4. The instrument ofclaim 3, wherein the parameter being measured includes temperature. 5.The instrument of claim 1, wherein measurement of the parameter by thesensors depends at least in part upon their temperature, the substratehas given thermal characteristics and the material filling the cavitieshave the given thermal characteristics of the substrate.
 6. Theinstrument of claim 5, wherein the parameter being measured includestemperature.
 7. The instrument of claim 1, wherein at least some of thesensors and said at least one electronic processing component areintegrated circuit die attached to bottoms of the cavities.
 8. Theinstrument of claim 1, wherein the material filling the cavitiesincludes a cured polymer and at least seventy percent by volume ofparticles of thermally conductive material.
 9. The instrument of claim8, wherein the material filling the cavities is electrically insulative.10. The instrument of claim 9, wherein the sensors and said at least oneelectronic processing component are attached to bottoms of the cavitiesby an adhesive material that contains particles of thermally conductivematerial and that is electrically insulative.
 11. The instrument ofclaim 10, wherein at least some of the sensors and said at least oneelectronic processing component are integrated circuit die attached tobottoms of the cavities.
 12. The instrument of claim 11, wherein theelectrical conductors are connected to the integrated circuit die bywire leads attached between the electrical conductors and bonding padsof the circuit die.
 13. The instrument of claim 12, wherein the materialfilling the cavities also extends around the wire leads for protectionof them.
 14. The instrument of claim 1, wherein the electricalconductors are encapsulated in an insulating film to which the pluralityof sensors and at least one electronic processing component arephysically attached in a manner to make electrical connections with theelectrical conductors therein.
 15. The instrument of claim 14,additionally comprising a rigid protective cover extending across thesubstrate over at least the sensors, said at least one electronicprocessing component and the electrical conductors encapsulated in aninsulating film.
 16. The instrument of claim 15, wherein the electricalconductors and the insulating film encapsulating them extend between theplurality of sensors and said at least one electronic processingcomponent in grooves formed in one of the substrate and cover, and thesubstrate and cover are rigidly attached to each other in abuttingsurface regions between the grooves.
 17. The instrument of claim 16,wherein the attached abutting surface regions of the substrate and coverextend over at least eighty percent of a common area of the substrateand cover.
 18. The instrument of claim 17, wherein the substrate andcover are each circular in shape with the same diameter.
 19. A measuringinstrument, comprising: first and second substrate portions heldtogether at a common interface, a plurality of cavities positionedbetween the first and second substrate portions, a plurality of groovespositioned between the first and second substrate portions and extendingbetween the plurality of cavities, strips of electrically insulativefilm with electrical conductors therein positioned within the grooves, aplurality of sensors of a parameter and electronic components positionedwithin the cavities and electrically connected with the electricalconductors in the film strips, and wherein the first and secondsubstrate portions are directly attached together in regions of theircommon interface between the grooves and cavities.
 20. The instrument ofclaim 19, wherein the first and second substrate portions are eachcircular discs having the same diameter.
 21. The instrument of claim 19,wherein the plurality of cavities and the plurality of grooves arearranged so that one or more patterns of segments of the film strips arerepeated across the interface between the first and second substrateportions, thereby to simplify manufacture of the instrument.
 22. Theinstrument of claim 21, wherein the sensors and electronic componentshave been attached to the film strip segments before installation in thecavities and grooves.
 23. The instrument of claim 19, wherein theregions of the first and second substrate portions that are directlyattached together exceed eighty percent of their common interface. 24.An instrument for measuring a parameter, comprising: a silicon wafersubstrate having opposing planar surfaces, a plurality of recessesformed in said one substrate surface at positions distributedthereacross and having bottom surfaces, a plurality of sensors in theform of silicon integrated circuit die attached to the bottom surfacesof at least some of the recesses, thereby providing measurements of theparameter at positions distributed across said one substrate surface, atleast one silicon electronic processing integrated circuit die attachedto the bottom surface of at least one of the recesses, electricalconductors extending across said one substrate surface between at leastthe recesses containing the integrated circuit die, lead wires extendingbetween and bonded to pads of the integrated circuit die and electricalconductors adjacent the recesses in which the die are attached, and aprotective material filling the recesses around the integrated circuitdie and extending around the lead wires.
 25. The instrument of claim 24,wherein the integrated circuit die are attached to the bottoms of therecesses by an adhesive that includes heat conductive particles.
 26. Theinstrument of claim 25, wherein the protective material includes heatconductive particles.
 27. The instrument of claim 26, wherein theadhesive and protective material are electrical insulators.
 28. Theinstrument of claim 24, additionally comprising at least one additionalelectronic component attached to the bottom surface of at least one ofthe recesses and connected with the electrical conductors adjacent theat least one component.
 29. A parameter measuring system, comprising: aportable measuring instrument comprising a substrate with a plurality ofsensors of the parameter spatially distributed there across, a firstelectronics system including a processor connected with the sensors anddata storage, a power storage system connected to operate the sensorsand electronics system, and a coil connected to at least receiveelectromagnetic energy for recharging the power storage system, adocking station comprising a surface that supports the measuringinstrument when inserted therein from a side, a module positioned abovethe supporting surface that contains a second electronics systemincluding a processor, a flexible film carried by an underside of themodule, a coil physically attached to the film and electrically drivenby the second electronics system to provide electromagnetic energy torecharge the power storage system of the measuring instrument, and amechanism carried by the underside of the module that lowers the film torest its coil on the coil of the measuring instrument when carried bythe surface in order to recharge the power storage system under controlof the first and second electronics systems.
 30. The system of claim 29,wherein the film is attached at one extreme to the underside of themodule and the lowering mechanism includes an electromagnetic deviceattached to an opposite extreme of the film for providing slack in thefilm to rest on the measuring instrument and relative tautness in thefilm to raise it above the measuring instrument.
 31. The system of claim29, wherein the surface of the docking station that supports themeasuring instrument includes a plurality of wheels upon which themeasuring instrument rests, the wheels being constrained to rotate aboutaxes which intersect in a center of the measuring instrument and beingpowered by individual electrical motors, thereby to rotate the measuringinstrument about said center when the electrical motors are energized.